[huhn]

are you using windows 7?

if yes this OS has huge issue with switching refresh rates.
you can try to use overlay or FSE to avoid this issue or change to a OS with a working desktop composition.

the composition is supposed to be the same as the desktop refresh rate.
and desktop refresh rate is the display refresh rate.
these composition rate mismatches are a huge problem on windows 7 and older.

the desktop refresh rate doesn't matter it is changed at the same time.